Intro to Proof / Proving Parallel Lines & Transversals

Lesson Prep

Lesson Details

• Duration: 50 minutes

• Learning Goal: Introduce proof structure in a non-math way and then transition towards proving parallel lines & transversal theorems.

Prework

• Make sure you have Chromebooks or some other class set of technology

Answer Keys

• Link to Answer Keys

Classwork

Google Slides

• Link to Slides

  • Taken from Ben Orlin

1:1 Devices Version

• Desmos Activity for Warm Up and Notes

• Spiraling Practice on paper (see below)

Paper Version

• Warm Up

  • Allow 15 minutes for research

• Notes

  • Look at example proofs in Google Slides before moving to notes

  • Also, the students can use this word bank to try some of the proofs

• Spiraling Practice

Standards

Common Core

• HSG.CO.C.9 – Prove theorems about lines and angles. Theorems include: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment’s endpoints.

TEKS

• G.4(A) – distinguish between undefined terms, definitions, postulates, conjectures, and theorems

• G.4(B) – identify and determine the validity of the converse, inverse, and contrapositive of a conditional statement and recognize the connection between a biconditional statement and a true conditional statement with a true converse

• G.6(A) – verify theorems about angles formed by the intersection of lines and line segments, including vertical angles, and angles formed by parallel lines cut by a transversal and prove equidistance between the endpoints of a segment and points on its perpendicular bisector and apply these relationships to solve problems